An electric oven is rated at 3.2 kW.
A digital alarm clock operates at a power of 4.0 W.
The oven rating is written in kilowatts.
Give the equivalent rating in watts.
Consider the oven working normally for one second.
State the quantity of energy it transfers in this time.
The oven operates continuously while a batch of food bakes for 7.5 minutes.
Calculate the energy transferred over this interval.
The clock must remain on until it has transferred as much energy as the oven does while baking the batch.
Calculate the required operating time for the clock.
Give your answer in hours.
128 exam-style questions on Edexcel GCSE Physics 8.3 Power and efficiency, covering 8.3.1 Power and 8.3.2 Efficiency. Each one has a worked solution and a mark scheme showing where the marks go.